An optical device includes a chip containing a vertical cavity surface emitting laser (vcsel) active region that produces a laser beam on a first axis. The vcsel can further include a post having a central axis offset a distance from the first axis. A lens can be mounted on the post such that it bends the laser beam away from the first axis. Alternately, the chip can include multiple vcsel active regions each of which produces a laser beam on a different axis. The chip can include a post having a central axis offset from the laser beam axes. A lens can be mounted on the post such that the lens bends the laser beams away from the central axis.
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#2# 6. An optical device comprising:
a chip containing a vertical cavity surface emitting laser (vcsel) active region that produces a laser beam on a first axis;
a post having a central axis therethrough, said central axis being offset a first distance from said first axis, said post being mounted on said chip;
a lens mounted on said post, said first lens being configured to direct said laser beam away from said first axis;
a monitor diode formed in the chip containing the vcsel active region, the monitor photodiode being positioned in the chip relative to the lens so as to receive a portion of light from the active region that reflects off the lens; and
wherein the chip, the post, and the lens have an overall package height of less than 2 mm.
#2# 1. An optical device comprising:
a chip containing at least one laser active region that generates a laser beam propagating in a first direction and having a first optical axis;
a polymeric post positioned on said chip;
a lens mounted on said post, said lens being positioned along a second optical axis to direct said laser beam away from said first direction;
wherein said lens is configured to direct at least a portion of said laser beam to a monitor photodiode formed in the chip containing the at least one active region;
the monitor photodiode being positioned in the chip relative to the lens so as to receive a portion of light from the vcsel that reflects off the lens; and
wherein the chip, the post, and the lens have an overall package height of less than 2 mm.
#2# 11. An optical device comprising:
a chip containing at least a first and a second vertical cavity surface emitting laser (vcsel) active region, said first vcsel active region being configured to produce a first laser beam on a first axis, said second vcsel active region being configured to produce a second laser beam on a second axis;
a polymeric post having a central axis therethrough, said central axis being offset from said first and second axes, said post being adjacent to said chip; and
a lens mounted on said post, said lens being configured to bend said first and second laser beams away from said central axis;
a monitor diode formed in said chip containing a first and second vcsel active regions, the monitor diode being positioned in the chip relative to the lens so as to receive a portion of the light from the first and second active regions that reflects off the lens; and
wherein the chip, the post, and the lens have an overall package height of less than 2 mm.
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Not applicable.
1. The Field of the Invention
Exemplary embodiments of the present invention relate to the field of laser optics, and, more specifically, to designs of Lens-on-Chip (LOC) and Lens-on-Post-on-Chip (LOPOC) Vertical Cavity Surface Emitting Lasers.
2. The Relevant Technology
Lasers have a wide range of applications in today's technological world. For example, lasers are used in data communications applications, in entertainment devices, as sensors, as measuring devices, and in a host of other applications. One type of laser used in these devices is the vertical cavity surface emitting laser (VCSEL). Over the years, the various devices that use VCSELs have become smaller and smaller. This has resulted in a technical challenge to engineers, who must design these components to be smaller and smaller, yet still perform to the same or better technical specifications.
One method used to miniaturize laser transmitters and laser transmission assemblies is to reduce the number of components. Another method is to make the various components themselves, smaller. For example, the beam of light that exits from a laser transmitter often needs to be focused or collimated. External lenses have been used for this purpose for many years. Recently, lens on chip (LOC) and lens on post on chip (LOPOC) technologies have been developed. LOC technology incorporates a polymer lens onto the laser chip during the wafer fabrication process. The fabrication process includes lithographically forming a region on the wafer to accept a polymer and subsequently placing the lens on the wafer using an inkjet or needle. LOPOC includes an additional polymer standoff to allow the lens to be raised from the surface of the laser chip, thus making it possible to achieve greater optical power. Previously, LOC and LOPOC were used to couple laser light from a VCSEL directly into a fiber, such as a fiber optic cable in a data communications network. This coupling was achieved on a single axis, the axis of the fiber optic cable and the axis of the light beam exiting from the VCSEL being co-linear.
One example of a basic LOPOC apparatus is shown in
Currently LOPOC devices only allow the beam to be directed in a straight line upward or downward, along the optical axis of the standoff and/or lens, i.e. on a single axis. However, to make the overall package smaller, it is sometimes desirable to tilt the beam or direct the beam to a point that is “off” this optical axis.
Unfortunately, the above design to tilt the beam suffers from some significant drawbacks. Most importantly, because of the large offset between lens 156 and emitter 152, system 150 takes up an undesirable amount of space. This limits the size of the various devices that can use these VCSEL assemblies.
Embodiments of the present invention provide a Vertical Cavity Surface Emitting Laser (VCSEL) that can be configured to direct a beam of light emitted from the laser to a point offset from an optical axis of the laser. Additionally, embodiments of the present invention can also reduce the overall height of the VCSEL as configured to enable the apparatus to be used in low profile devices. In this manner, embodiments of the present invention can be used in low profile devices that cannot physically be built using prior art technology. Illustrative devices can include, by way of example and not limitation, optical mice, optical pens, paper sensors, and other devices that use small lasers to perform various functions.
In one embodiment, a VCSEL is disclosed that includes a chip containing a VCSEL active region that produces a laser beam on a first axis. The VCSEL can further include a post having a central axis therethrough. The central axis of the post can be offset a distance from the first axis. The VCSEL can further include a lens mounted on the post such that it bends or directs the laser beam away from the first axis.
In an alternate embodiment, a VCSEL is disclosed that includes a chip containing at least a first and a second VCSEL active region. The first VCSEL active if region produces a first laser beam on a first axis, while the second VCSEL active region produces a second laser beam on a second axis. The VCSEL can further include a post having a central axis therethrough. The central axis of the post can be offset from both of the first and second axes. The VCSEL can further include a lens mounted on the post such that the lens bends or directs the first and second laser beams away from the central axis. The lens can be designed to focus, collimate, or diverge the laser beam, as desired.
In both of the above embodiments, the post can be made from a photoresist material, including, but not limited to, SU-8 and Benzocyclobutene. The lens can be made from an optical epoxy that is deposited via ink jet or other manners onto the post. In some of the embodiments, the lens can be used to focus a portion of the laser beam(s) onto a photodiode or other optical receptor. These embodiments can be used in low profile devices that cannot physically be built using prior art technology. Illustrative devices can include, by way of example and not limitation, optical mice, optical pens, paper sensors, and other devices that use small lasers to perform various functions.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Embodiments of the present invention provide an apparatus that can direct a beam of light emitted from a laser to a point offset from an optical axis of the laser. Additionally, embodiments of the present invention can also reduce the overall height of the apparatus to enable the apparatus to be used in low profile devices. In this manner, embodiments of the present invention can be used in low profile devices that cannot physically be built using prior art technology. Illustrative devices can include, by way of example and not limitation, optical mice, optical pens, paper sensors, and other devices that use small lasers to perform various functions. Various embodiments of such an apparatus are discussed below.
With continued reference to
To aid with controlling the degree of bending or tilting of laser beam 210 relative to the perpendicular to the surface of chip 202, the lens/standoff combination is not centered directly over laser emitter 204, but is offset a distance from the center, the distance being identified as by reference “A”. For instance, a longitudinal axis of standoff 206 and the central axis of lens 208 can be offset from an axis of laser beam 210 emitted from laser emitter 204 before laser beam 210 enters lens 208. This offset distance can be from 0 micrometers (μm) to about 200 μm, more preferably from about 50 μm to about 75 μm, or other distances outside the identified ranges. This offset allows a laser beam 210 transmitted from laser emitter 204 to be bent or directed at an angle from the perpendicular by lens 208, and focused to a point 212. The exact angle of the bend or tilt can depend on the height and shape of lens 208. In exemplary embodiments, this angle can be from about 10° to about 45° from the perpendicular, although other angles are possible. Further, although reference is made to lens 208 focusing the beam, it can be understood that in other configurations the lens can be designed to focus, collimate, or diverge the laser beam, as desired.
The specific direction of beam 210 shown in
To reduce reflections and other undesirable optical effects, standoff 206 can be in physical contact with chip 202. In one exemplary embodiment, standoff 206 can be attached to chip 202 using, for example, an optically clear adhesive. Similarly, lens 208 can be in physical contact with polymer standoff 206. In one embodiment, lens 208 can be attached to polymer standoff 206 using, for example, an optically clear adhesive. In alternate embodiments, chip 202, polymer standoff 206, and lens 208 can be held in physical contact with each other using a frame or housing (not shown). In yet other alternate embodiments, chip 202, polymer standoff 206 and lens 208 can be optically aligned without being in physical contact with each other.
The standoff 206 and lens 208 can be fabricated from similar or dissimilar polymers. In one embodiment, standoff 206 can be fabricated from a photoresist material. A photoresist material can be defined as a light sensitive liquid or film, which, when selectively exposed to light and then developed, masks off an area based upon the configuration of a photomask positioned above the photoresist material. In one process, by way of example and not limitation, the photoresist material can be uniformly deposited on the surface of chip 202. A photomask can then be applied, and undesired portions of the photoresist material can be removed by exposing the photoresist material uncovered by the photomask to selected light or radiation, thus forming standoff 206 in a desired location on chip 202. In some embodiments, larger than normal chips can be fabricated to allow for an additional standoff distance. In some embodiments, the photoresist material can be SU-8, Benzocyclobutene (BCB), or other photoresist materials known to those of skill in the art.
The lens 208 can be fabricated from, by way of example and not limitation, an optical epoxy. Once standoff 206 is formed on the surface of chip 202, a lithographic process, or other processes known to those of skill in the art, can be used to deposit the optical epoxy onto the top surface of standoff 206. In one embodiment, lens 208 can be formed by using an ink jet process to deposit the polymer on top of standoff 206. The specific shape of lens 208 can be determined by, among other things, operational considerations. For example, lens 208 can be designed to produce a converging beam 210, as shown in
VCSEL 200 can have various configurations to generate laser beam 210 by way of stimulated photonic emission. For instance, and not by way of limitation, VCSEL 200 can be an air post VCSEL, a buried re-growth VCSEL, or other types of VCSELs that incorporate a plurality of Distributed Bragg Reflectors (DBRs). Specific construction/manufacturing techniques for VCSELs are known to those of skill in the art. The VCSEL 200 can be operated at a wavelength of between about 650 nm and about 1500 nm. However, other wavelengths, both below and above this range, are also possible.
Similarly, the configuration of chip 202 can vary based upon the general functionality of VCSEL 200. VCSEL chips can, in general, be manufactured as a wafer of many chips that can then be cleaved into individual chips. As noted above, the specific dimensions of chip 202 can vary depending on the specific application, wavelength, and degree of offset of standoff 206. It is therefore understood that the specific illustrated embodiments provide examples only, and should not be construed to limit the invention in any way.
To aid with controlling the degree of bending or tilting of laser beam 210 relative to the perpendicular to the surface of chip 202, the lens/standoff combination is not centered directly over laser emitter 204, but is offset a distance from the center, the distance being identified as by reference “A”. For instance, a longitudinal axis of standoff 206 and the central axis of lens 208a are offset from an axis of laser beam 210 emitted from laser emitter 204 before laser beam 210 enters lens 208a. This offset distance can be from 0 micrometers (μm) to about 200 μm and more preferably from about 50 μm to about 75 μm. This offset allows a laser beam 210 transmitted from laser emitter 204 to be bent or directed at an angle from the perpendicular by lens 208a, and further directed at an angle by external lens 214. Lens 208a has a slightly different shape, and correspondingly different optical properties, than lens 208 of
The specific direction of beam 210 shown in
The photodiode 406 measures a portion of beam 412 that is reflected from lens 410 as beam 412a. Photodiode 406 allows an operator to monitor the laser power from laser 404. In some embodiments, this power can then be adjusted according to operational requirements to more effectively control operation of laser 404.
While the exemplary embodiments shown in
Mounted to chip 502 and optically communicating with laser emitters 504a and 504b is a standoff or post (not shown in this view) that supports a lens 508. The standoff facilitates propagation of a laser beam 510a emitted by laser emitter 504a and a laser beam 510b emitted by laser 504b, to lens 508. Lens 508 directs both laser beams 510a, 510b toward a point 512a, 512b respectively, offset from an axis of laser beams 510a, 510b emitted by laser emitters 504a, 504b.
In this manner, VCSEL 500 can direct both laser beams 510a, 510b in a path “off axis” to a perpendicular to the surface of chip 502, without using optical components external to VCSEL 500. By so doing, VCSEL 500 provides a smaller overall package size than is currently available with the VCSEL shown in
To aid with controlling the degree of bending or tilting of laser beams 510a, 510b relative to the perpendicular to the surface of chip 502, the lens/standoff combination is not centered directly over laser emitters 504a, 504b, but is offset a distance from the center, the distance being identified as by reference “A”. In one exemplary embodiment, the lasers 504a, 504b and lens 508 can be spaced such that the offset distance “A” between lasers 504a, 504b and the center of lens 508 are the same. In alternate embodiments, the offset distance can be different for each laser emitter 504a, 504b.
This offset allows a laser beam 510a transmitted from laser emitter 504a, and a laser beam 510b transmitted from laser emitter 504b, to be bent at an angle from the perpendicular by lens 508. In exemplary embodiments, this angle can be from about 10° to about 45° from the perpendicular, although other angles above or below those identified are possible. In one exemplary embodiment, the angle is about 45° from the perpendicular for each beam. The specific direction of the beams shown in
In some embodiments, it is possible to direct both beams 510a, 510b to a single point, such as, by way of example and not limitation, an optical fiber. In this case, beams 510a and 510b would be operated on different frequencies so that they could be coupled into the same fiber.
Another alternate exemplary embodiment of a laser with multiple active regions is shown in
In this manner, VCSEL 550 can direct all three laser beams 560a, 560b, 560c in a path “off axis” to a perpendicular to the surface of chip 552, without using optical components external to VCSEL 550. By so doing, VCSEL 550 provides a smaller overall package size than is currently available with the VCSEL shown in
To aid with controlling the degree of bending or tilting of laser beams 560a, 560b, 560c relative to the perpendicular to the surface of chip 552, the lens/standoff combination is not centered directly over laser emitters 554a, 554b, 554c but is offset a distance from the center, the distance being identified by reference “A”. In one exemplary embodiment, the lasers 554a, 554b, 554c and lens 558 can be spaced such that the offset distance “A” between lasers 554a, 554b, 554c and the center of lens 558 are the same. In alternate embodiments, the offset distance can be different for each laser emitter 554a, 554b, 554c. In yet other alternate embodiments, the offset distance can be the same for two of the emitters, and different for the third.
This offset allows a laser beam 560a transmitted from laser emitter 554a, a laser beam 560b transmitted from laser emitter 554b, and a laser beam 560c transmitted from laser emitter 554c, to be bent at an angle from the perpendicular by lens 558. In exemplary embodiments, this angle can be from about 10° to about 45° from the perpendicular, although other angles above or below those identified are possible. In one embodiment, the angle is about 45° from the perpendicular for each beam. However, different angles for each beam are also possible. The specific direction of the beams shown in
The embodiments of
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
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